This invention relates to a piling rake with pivotally mounted teeth which pivot away from objects that provide a certain degree of resistance and which has a hydraulic system for returning the teeth to the original position when each tooth clears the objects.
In logging operations, it is frequently necessary to clear sites of logging slash, brush and other debris prior to reclamation of the land for reforestation purposes. In the past, bulldozers or skidders with conventional blades have been used to push the slash, lower portions of the blades being fitted with fixed rigid teeth spaced between three and four feet apart on the blade. The blade must be raised so the teeth will clear rocks and stumps and the teeth are prone to breaking when they strike such objects.
To try to overcome these problems, attempts have been made to provide spring-loaded teeth which are pivotally mounted so they will gave way when stones, stumps or other such objects are encountered. The hope was that the teeth would deflect when a heavy or stationary object is encountered and then spring back to the normal position after the object is cleared. The general principle is somewhat similar to the ridge leveler blade shown in U.S. Pat. No. 1,744,801 to Rimple which is so constructed that it gives when a rigid obstruction is encountered. Similarly, U.S. Pat. No. 1,511,292 to McLeod discloses a stone rake with yieldable spring biased teeth. U.S. Pat. No. 1,929,799 to Weeks and U.S. Pat. No. 1,876,867 to Dean also disclose scrapers with yieldable blades.
As applied to piling rakes suitable for clearing land in timber operations, it has been found that spring-biased blades provide distinct disadvantages. Firstly, extremely heavy springs are required to provide the necessary resistance so that the teeth will have the necessary pushing force and will yield only when they encounter large rocks, stumps and similar things. Such heavy springs require strong and heavy mounts, complicating the design, and are prone to breaking. Additionally, an extreme hazard is created when the resiliently biased teeth snap back to their original position after the object is cleared. They are liable to strike some object, such as a small stone, and propel it a considerable distance. The danger to persons working in the area is apparent and means that such a device would likely fail to receive approval from authorities concerned with the safety of workers.
Other prior art include U.S. Pat. No. 2,912,774 to McCrary which discloses retractable ripper teeth for a bulldozer blade, U.S. Pat. No. 2,932,100 to Goethe which shows a conventional brush raking arrangement for tractors and U.S. Pat. No. 2,985,973 to Struemph which discloses a self-cleaning timber rake with a movable cleaning bar.